1. Field of the Invention
The present invention relates to a tape cassette, and more particularly to a tape cassette in which a drop-out or an error may not occur during regenerating the information recorded on the tape.
2. Description of the Related Art
In the conventional tape cassette as shown in FIG. 4, a pair of hubs 1' around which a tape 2' is wound are accommodated in a cassette case C'. In the following description, the explanation will be given to only one of the hubs 1', but the same should be applied to the other hub 1'. The tape 2' wound around the hub 1' comprises a magnetic tape and a leader tape. One end of the magnetic tape is connected to one end of the leader tape. As shown in FIG. 5, the other end of the leader tape, i.e., a base end part 21' of the tape 2' is engaged between an engagement cavity 11' recessed on the outer periphery of the hub 1' and a clamper 12' fitted into the engagement cavity 11'.
In the tape cassette described above, when the base end part 21' of the tape 2' is engaged between the engagement cavity 11' and the clamper 12', and the tape 2' winds around the hub 1', a stepped part or a gap is formed as represented by phantom lines in FIG. 6 (phantom lines are shown in the left side end only for convenience of illustration). Accordingly, "transcription phenomenon" occurs, that is, the tape 2' which winds around the hub 1' having the stepped part or the gap is subjected to marks or traces impressed at the part corresponding to the stepped part or the gap of the hub 1'. The marks or traces thus impressed are sequentially transcribed to the following winding layer of the tape 2' (tape 2' is omitted in FIG. 6 for convenience of illustration). In particular, on the tape surface adjacent to the hub 1', the transcribed linear marks perpendicular to the longitudinal direction of the tape 2' stand out. When the tape 2' having such transcription marks impressed thereon is used to record or reproduce signals, signal omission is liable to occur at the transcription marks, thereby causing drop-outs or errors.
To reduce such errors, extensive investigations have been made to provide a hub 1' having no stepped part as represented by phantom lines in FIG. 6. However, even with the hub 1' having no stepped part, the errors cannot be completely eliminated.